Re: [Intel-gfx] [PATCH] drm/i915/psr2: Do full fetches when doing async flips

["Souza, Jose" <jose.souza@intel.com>]

On Thu, 2021-10-28 at 16:32 +0300, Ville Syrjälä wrote:
> On Wed, Oct 27, 2021 at 11:48:55AM -0700, José Roberto de Souza wrote:
> > Async flips are not supported by selective fetch and we had a check
> > for that but that check was only executed when doing modesets.
> > So moving this check to the page flip path, so it can be properly
> > handled.
> > 
> > This fix a failure in kms_async_flips@test-cursor.
> > 
> > Cc: Mika Kahola <mika.kahola@intel.com>
> > Cc: Jouni Hogander <jouni.hogander@intel.com>
> > Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_psr.c | 8 ++------
> >  1 file changed, 2 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
> > index 8d08e3cf08c1f..ce6850ed72c60 100644
> > --- a/drivers/gpu/drm/i915/display/intel_psr.c
> > +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> > @@ -729,12 +729,6 @@ static bool intel_psr2_sel_fetch_config_valid(struct intel_dp *intel_dp,
> >  		return false;
> >  	}
> >  
> > -	if (crtc_state->uapi.async_flip) {
> > -		drm_dbg_kms(&dev_priv->drm,
> > -			    "PSR2 sel fetch not enabled, async flip enabled\n");
> > -		return false;
> > -	}
> > -
> >  	/* Wa_14010254185 Wa_14010103792 */
> >  	if (IS_TGL_DISPLAY_STEP(dev_priv, STEP_A0, STEP_C0)) {
> >  		drm_dbg_kms(&dev_priv->drm,
> > @@ -1592,6 +1586,8 @@ static bool psr2_sel_fetch_pipe_state_supported(const struct intel_crtc_state *c
> >  {
> >  	if (crtc_state->scaler_state.scaler_id >= 0)
> >  		return false;
> > +	if (crtc_state->uapi.async_flip)
> > +		return false;
> 
> This looks dodgy. Pretty sure we can't turn off this thing during
> an async flip. So I think the correct short term fix is to not do
> async flips with psr2 enabled. The longer term fix would involve
> using the same approach Stan is preparing for the async flip
> watermark tweaking, which is to convert the first async flip into
> a sync flip.
> 

It is not turning PSR2 off, it is telling hardware to fetch the whole memory of all planes and send the whole screen to panel instead of fetching and
sending a smaller area for this frame, we also do that when a plane is moved to a negative coordinate.